1. Technical Field
The present invention relates to a method of controlling an ODD archive system, and more specifically to a method of setting a parity drive in an archive system including optical disc drives.
2. Discussion of the Related Art
RAID (“Redundant Array of Independent Discs) is a technology that distributively stores data in a plurality of hard disc drives (HDDs). RAID levels are divided according to data storing manners. Reliability or entire capability of a storage device may be increased corresponding to each RAID level.
There were five RAID levels originally conceived, but many variations including several nested levels have evolved. RAID combines a plurality of discs into a single logical disc.
RAID 0 uses two or more stripped discs without parity for error detection, and RAID 1 uses two or more mirrored discs without parity. Thus, RAID 0 and RAID 1 provide failure prevention functions in preparation for disc errors or single disc failure.
RAID 3 and RAID 4 use three or more stripped discs with simple parity. For example, in the case of using four discs as shown in FIG. 1, various types of recording-requested data, such as music files, movie files, or document files, are distributively recorded in three discs, and parity is intensively recorded in one remaining disc for error detection.
RAID 5 uses three or more stripped discs in which parities are distributed. For example, in the case of using five discs as shown in FIG. 2, data are distributively recorded in the five discs and parities for error detection are distributed over the five discs. RAID is well known to those of ordinary skill in the art, and thus, further detailed description will be omitted.
Recently, ODD archive systems, such as juke boxes, are commercially available. For reference, a substantial difference between ‘archive’ and ‘back-up’ lies in the fact that ‘archive’ is to store and manage data sources, but ‘back-up’ stores and manages data copies.
An ODD archive system may include a drive bay having a plurality of ODDs (Optical Disc Drives). For example, in the case of storing data in RAID 3 and 4 in an archive system provided with a drive bay having first to fourth ODDs Drive 1 to 4, the archive system distributively records data in first to third optical discs inserted into the first to third ODDs Drive 1 to 3 and intensively records parity for error detection in fourth optical disc inserted into the fourth ODD Drive 4.
However, in the case where among the first to fourth ODDs, the fourth ODD Drive 4 is only subjected to use as a parity drive, excessive load is exerted to the fourth ODD with high frequency of use, thus sharply lowering durability of the fourth ODD and causing failures to the ODD archive system.